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    Subject[RFC PATCH v1 06/13] mm: add lru_[un]lock_all APIs
    Date
    Add heavy locking API's for the few cases that a thread needs exclusive
    access to an LRU list. This locks lru_lock as well as every lock in
    lru_batch_locks.

    This API will be used often at first, in scaffolding code, to ease the
    transition from using lru_lock to the batch locking scheme. Later it
    will be rarely needed.

    Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
    ---
    include/linux/mm_inline.h | 32 ++++++++++++++++++++++++++++++++
    1 file changed, 32 insertions(+)

    diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
    index ec8b966a1c76..1f1657c75b1b 100644
    --- a/include/linux/mm_inline.h
    +++ b/include/linux/mm_inline.h
    @@ -178,6 +178,38 @@ static __always_inline void move_page_to_lru_list_tail(struct page *page,
    __add_page_to_lru_list_tail(page, lruvec, lru);
    }

    +static __always_inline void lru_lock_all(struct pglist_data *pgdat,
    + unsigned long *flags)
    +{
    + size_t i;
    +
    + if (flags)
    + local_irq_save(*flags);
    + else
    + local_irq_disable();
    +
    + for (i = 0; i < NUM_LRU_BATCH_LOCKS; ++i)
    + spin_lock(&pgdat->lru_batch_locks[i].lock);
    +
    + spin_lock(&pgdat->lru_lock);
    +}
    +
    +static __always_inline void lru_unlock_all(struct pglist_data *pgdat,
    + unsigned long *flags)
    +{
    + int i;
    +
    + spin_unlock(&pgdat->lru_lock);
    +
    + for (i = NUM_LRU_BATCH_LOCKS - 1; i >= 0; --i)
    + spin_unlock(&pgdat->lru_batch_locks[i].lock);
    +
    + if (flags)
    + local_irq_restore(*flags);
    + else
    + local_irq_enable();
    +}
    +
    /**
    * page_lru_base_type - which LRU list type should a page be on?
    * @page: the page to test
    --
    2.16.1
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